Fig. 5From: A robust multi-feature based method for distinguishing between humans and pets to ensure signal source in vital signs monitoring using UWB radarFour VIMFs obtain by VMD and the corresponding spectrum of fast Fourier transform (FFT) of the signal shown in Fig. 4. a VIMF1, also regarded as the respiration. b VIMF2, also regarded as the heartbeat. c VIMF3. d VIMF4Back to article page